1. Field of the Invention
The present invention relates to a spray device for an ink-jet printer and, more particularly, to a spray device for achieving enhanced printer operation by using a multi-layer membrane made up of multiple interlayers each having different coefficients of thermal expansion.
2. Discussion of Related Art
An improved spraying device contrived to solve these problems is described in U.S. patent application Ser. No. 08/884,489 entitled Spray Device for InkJet Printer and a Method Thereof by Ahn Byung Sun. In this disclosure, a single-layer membrane made of a uniform material having a high heat-conductivity, e.g., Ag, Al, Cd, Cs, K, Li, Mg, Mn, Na or Zn is disclosed. Thus, though the upper portion of the membrane (that in contact with the ink chamber) and the lower portion of the membrane (that in contact with the heating chamber) have identical coefficients of thermal expansion, they have different thermal expansion rates due their adjacent materials, leaving the upper portion at a lower temperature and with a slower rate of volume variation. Therefore, the upper portion of the membrane tends to open in fissures.
Also, since there is no difference of the contracting rate with respect to the heat variation between the upper and lower portions of the membrane, the suction force of ink from the ink via to the ink chamber through the ink channel is small. Consequently, after expansion, it takes a long time for the ink to return to its original state, which affects the ink supplying speed and thus slows the overall printing speed.